There has been known a motorcycle having a vehicle body frame which conforms to a shaft drive method. For example, see Japanese Accepted Patent Publication Sho63 (1988)-35477 (page 6, FIG. 4)
According to the figure, the conventional rear arm bearing structure of the motorcycle is constituted of a structure in which a propeller shaft is accommodated in a rear arm, and the rear arm is mounted on a pair of left and right brackets (including bearing pipes) which are integrally formed on the main frame.
However, in the rear arm bearing structure of the motorcycle described above, the pair of left and right brackets (pivot plates) have U-shaped bent portions, wherein when a force which bends the bent portions is increased and, the irregularities of the force applied to the bent portions are also increased depending on parts of the bent portions and hence, it is difficult to increase the strength of pivot plates while reducing the weight of the motorcycle.
Accordingly, it is an object of the present invention to provide a motorcycle which can increase the strength of a pivot plate.